Add function for handling json responses

[jrgmartin]

Should live in the template controller?

/**
     * Takes the given parameters and returns a formed JSON string
     * @param string $state success/error
     * @param mixed $data the data to be returned
     * @param string $layout the HTML to be returned
     * @param null|array $errors
     * @param null|array $extra any additional array pairs to return
     * @param string $type
     */
    public function response($state, $data, $layout = null, $errors = null, $extra = null, $type = 'json') {

        if($type == 'json') {

            $json = array(
                'state' => $state,
                'data' => $data,
                'layout' => $layout,
                'errors' => $errors
            );

            if($extra) $json = array_merge($json, $extra);

            echo json_encode($json);
        }
    }